In the course of semiconductor fabrication, processes in which after being treated by heating wafers are cooled include: thermosetting of photoresists in photolithography with coater/developers; heating/baking of low-dielectric-constant, i.e. low-k, insulating films; CVD film deposition in forming metal interconnects and dielectric layers; and processes in etchers.
Heat-treatment of the wafers in these processes has conventionally been carried out using heaters made of aluminum or ceramic. In particular, wafers are placed onto the outer face of heaters in which a heating element is formed, utilized to control heating while the wafers undergo processes such as thermosetting of photoresists and heating/baking of low-k films, or CVD film deposition and etching.
Recently, in order to enhance productivity in these processes, it has become necessary to raise cooling speed for the post-heating heaters. By the same token, designing for rapid cooling of the processed articles to improve their characteristics has become widespread, and in particular, accompanying the enlarging of wafer diametric span demands for enhanced cooling speed have been growing.
Forcible liquid cooling and air cooling have been adopted in order to rapidly cool the heater in semiconductor manufacturing equipment applications to date. In specific terms, a cooling block is installed on the heater, usually on the reverse side, and by circulating through the block a liquid or air as a heat-transferring medium for cooling, heat is carried away from the heater, heightening the cooling speed.
Nevertheless, with these forcible liquid cooling and air cooling systems, the fact that large-scale devices are necessary for circulating the heat-transferring medium and for radiating heat has proved to be a cost-increasing factor in semiconductor manufacturing. Likewise, with it not being possible to enlarge the capacity for the heat-transferring medium within the limited space of the heater, significant improvement in heater cooling speed has been difficult.